This invention relates to compositions of matter classified in the art of chemistry as high solids polymer compositions including latices useful in filling relatively deep surface defects in cellulosic boards such as plywood veneer layers and the like. The compositions are also useful in filling surface imperfections in other articles such as flake and composition boards as sandable fillers free of metallic lead for smoothing irregular sheet metal work as in fabrication or of automobile and truck bodies and for smoothing irregularities in wood, metal, or plastic boat hulls, and the like.
The use of plywood as a construction material and as panelling is extensive and well known. Typically plywood is prepared by laminating thin sheets of wood which have been peeled circumferentially from a log. Lamination is by adhesives, usually urea-formaldehyde or phenol formaldehyde, normally under heat and pressure. During the peeling operation knots and other imperfections are cut through and carried along with the sheet. The use of sheets with voids from such defects or from knots that have become detached from the sheet to leave holes for face veneers on plywood results in an unattractive surface unsuitable for decorative use. Such sheets although structurally sound are less valuable commercially. Blemishes may also be introduced by gouging or other impacts and like treatment. Such defects as well as splits and cracks also reduce the value of the plywood for decorative purposes. They also make it difficult to apply a smooth laminas topcoat to the wood because the irregularities are reflected through to the topcoat surface. Hand patching of the larger blemishes by cutting out a standard shape encompassing the blemish or the missing knot and replacing it with a shaped wooden plug secured by adhesive has long been the industry practice. The disadvantages of this procedure are obvious. Smaller defects have been filled by mastic like material but hand operation for filling of each individual defect has been the rule here also. Neither operation provides the economies of automatic operation and large scale rapid filling and handling of the boards in the blemish repairing operation and thereafter.
The present invention provides a process which does exactly this.